Adopt a Useless Talent

For example

Whistling
Ear Wiggling
Remembering Lyrics
Always knowing the word someone has on the tip of their tongue

Being able to make a 3 leaf clover with their tongue
Remembering useless facts

Not just any whistling, but the kind that makes random strangers drop whatever they're doing to stop and listen. I heard a guy do this once; I was floored. I can't even describe it.

Being at ease with reading upside-down text.

Knowing how many stairs are in a staircase with a half-second glance, without actually counting.

Being able to lick their elbow

One of my teachers could write with both of his hands...starting from the center, he'd write mirrored letters with his left in the left direction and normal letters with his right hand in the right direction. Simultaneously.
It looks really amazing, but I'm still unsure what the practical use would be.

Sorry... (te-he) but I hear this one all the time...
Underwater Basket Weaving!
Okay... so it might have some practical application, but in most situations, pretty useless.
And a really useless one:
Being able to start or pause a dishwasher, washing machine/dryer telepathically at any time. Please note that you must still manually set them, open them, etc. All you have control of is the start and pause button.

One more... as a non-villian: having a constant cell signal dampener about you, yeah. You can't use a cell phone or a computer, awesome superpower, huh?

Memorizing world flags. Fun, but utterly useless...

Being able to hyperextend your elbow.

Being able to snap with your toes.

Being able to overhand serve a volleyball with one hand (toss and all).

The ability to burp on command.

I have all of these. Fun as they might be, they serve no purpose other than entertaining myself when I'm bored.

Being able to write upside down
Always knowing where to find certain quotes in a book

My history teacher can do the first, and I'm fairly good at the second - always useful in English.

Being able to touch your nose with your tongue (I can do this, and I've never found a practical use for it; people just seem to think it's impressive :|)

singing the alphabet backwards... i can actually do this and have only met one other person (that i remember) who could. it is useless other than entertaining yourself and being random.

Bending your thumb back to meet your wrist
Memorizing the entire script of a video/movie/book (for me it's Llamas With Hats :D)
Speaking in binary/knowing ascii
Memorizing song artists/albums/release dates

Hooray for my useless talents!

Being able to write without getting inkstains on your fingers.
Being able to step on the one squeaky board every time she visits (stolen from Brautigan)
Being able to locate the piece of fruit that will always go bad the day after
Being able to chop onions without crying.
Being able to squeegee windows perfectly while stopped at the gas station

Being able to stack pens to make a perfect square tower.
Being able to compare people to animals.

Being able to move your arms from latched behind your back (one elbow up, one elbow down) to clasped in front of you without letting go once (I can do this. I call it my "flexibility magic trick" and it's about the only thing I could ever do for a talent show.)
Being fluent in Pig Latin.
Never getting mixed up about what day it is.
Breaking things! (I totally stole this from one of my favorite series, Alcatraz Versus the Evil Librarians, by Brandon Sanderson.)
Being able to tell exactly how much soap will be needed for a load of laundry.
Being able to memorize foreign alphabets (but not what the letters sound like/mean).

remember pointless idioms.
always wearing mismatching socks.
finding cool things that are plastic (swords, hats, toys.)

I used to have this one: the human scales! I used to be able to tell how much a suitcase, book or anything weighs just by holding it with one or both hands. Was nearly exact, almost to the grams. For the record, I acquired this ability during a time in which I had to travel a lot, and carry just enough stuff not to pay excess weight, to not document anything, etc.

Being able to drown fish.
Memorizing random quotes from anime/manga ("I'll take a potato chip... and eat it!" -Light Yagami, Death Note).
The sheer klutziness that allows one to walk into stop and yield signs.
Being able to find some way for "that's what she said" to work in any sentence/phrase no matter the context.
Coming up with useless poems (There once was a rabbit who lived in a tree and he said to the bird, "I love thee!" But then the bird ate the rabbit.).

The ability to drown fish.
Memorizing random anime/manga quotes ("I'll take a potato chip... and eat it!" -Ligh Yagami, Death Note).
Coming up with useless poems (There once was a rabbit who lived in a tree and he said to the bird, "I love thee!" But then the bird ate the rabbit.).
The sheer klutziness that allows for one to walk into STOP and YIELD signs.
Pretending to know Morse Code.
Practicing writing Japanese in one's spare time.
The ability to sleep anywhere.

Biting your toenails, totally useless (but fun for fantasy characters)
Knowing all the names of the moons of Jupiter, or any of the other planets' moons in our solarsystem